This invention relates generally to solid-state lasers and, more particularly to apparatus which combines in a common gain medium the operations of producing a TEM.sub.oo laser beam and amplifying the beam.
A laser usually includes an active medium located within an optical resonator. In a stable laser resonator, conventionally used to achieve a TEM.sub.oo beam profile, it is usual to introduce an aperture to narrow the oscillator beam so that only a transverse mode can emerge. However, such aperturing of the oscillator beam is very costly in terms of lost energy. Typically, a laser oscillator using a 6.35 mm diameter by 4 inches long ruby crystal may produce one joule of energy when operating multimode open aperture, but when the beam is apertured with a 1.75 mm aperture in order to produce a TEM.sub.oo output, only about 80 millijoules of energy is produced. This difference in energy is stored in the crystal and is wasted.
It is a primary object of the present invention to provide a resonator configuration which combines in a single laser crystal the operations of a narrow beam oscillator and a large volume amplifier.